Miniature laser grown onto silicon chip could revolutionise computing

• Silicon chips have revolutionized communications, but their operation has evolved to replace electrons with photons for information storage and manipulation.

• A study in Nature reported the fabrication of the first miniaturised lasers directly on silicon wafers, marking a significant advance in silicon photonics.

• Photons carry information faster, with greater data capacity and lower energy losses than electrons.

• The challenge of using photons is integrating the source of these particles — a light source — with the silicon chip itself.

• Currently, engineers attach a separate laser light source to the chip, which operates more slowly due to small but significant mismatches and is more expensive.

• The researchers “grew” the laser directly on a silicon chip, a process that is more scalable and compatible with existing manufacturing methods.

• The process involved a silicon wafer base, nanometre-sized ridges through which photons travelled, and a small region that produced these photons.

• The researchers carved nanometre-wide ridges in a 300-mm-long silicon wafer and applied silicon dioxide as the insulating material.

• The researchers deposited three layers of indium gallium arsenide on the same wafer, which together functioned as the laser.

• The researchers added electrical contacts connected to an external current source to make the laser work.

• The researchers were able to embed 300 functional lasers on a single 300-mm silicon wafer, producing light with a wavelength of 1,020 nm, which is well-suited for short-ranged transmissions between computer chips.

• The laser could continuously operate for 500 hours at room temperature (25° C), but efficiency dropped at around 55°C.

• The photonic silicon chip is the first demonstration of a fully monolithic laser diode on a silicon wafer of this size, making it scalable and cost-effective.